<?php
namespace Drupal\hello_world\Plugin\Block;

use Drupal\Core\Block\BlockBase;

/**
 * Provides a 'Hello' Block
 *
 * @Block(
 * id = "hello_block",
 * admin_label = @Translation("Hello block"),
 * )
 */
class HelloBlock extends BlockBase{

  /**
   * {@inheritdoc}
   */
  public function build() {
    $builtForm = \Drupal::formBuilder()->getForm('Drupal\hello_world\Form\FirstForm');
$renderArray['form'] = $builtForm;

return $renderArray;
  }
}
